Synthesis, structure of 3D lanthanide (La(III), Pr(III)) nanoporous coordination polymers containing 1D channels as selective luminescent probes of Pb 2+, Ca 2+ and Cd 2+ ions

Abstract

Two kinds of 3D coordination polymers, namely, {[La 2(PDA) 3(H 2O) 4]·H 2O} ∞ ( I) and {[Pr 2(PDA) 3(H 2O) 3]·H 2O} ∞ ( II) have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermal analyses and single crystal X-ray diffraction. In complex I, La(III) ions are nine-coordinated and ten-coordinated and have N 1O 8 or N 1O 9 polyhedral units connecting to the PDA 2− anions forming tricapped trigonal prism and double-capped cubic antiprism geometries, respectively. Two types of ring motifs as building blocks constructed by La 8C 2O 10 (20-membered ring) and La 4C 2O 6 (12-membered ring) are connected alternately into a highly ordered 2D sheet and further assembled into a nanoporous 3D coordination polymer with parallel channels. In complex II, Pr(III) ions are eight-coordinated and nine-coordinated and have N 1O 7 or N 2O 7 polyhedral units connecting to the PDA 2− anions forming trigonal dodecahedron and tricapped trigonal prism configurations, respectively. The tetranuclear homometallic motifs formed by Pr 4C 4O 8 unit (16-membered ring), acting as the building blocks, are constructed into a 3D coordination polymer. Luminescent emissions of the lanthanide-based MOF of complexes I and II have been measured in the solution of DMF at room temperature, which reveal that they presenting ion-selective characters toward certain metals, such as Pb 2+, Ca 2+ and Cu 2+ or Cd 2+ ions.